My Opinion
I think that is the viewer and the observed angles between objects, observing and being observed that the balance of power between objects.
Vertical composition can fully reveal the differences in the distribution rights will be observed the object viewer, and demonstrated the power of the poor, high angles of, viewer's position is more power; low angles in, viewer in a weak position.
Horizontal Angles more of a performance of the details of the observed object, viewer from different directions to observe the same objects, all-round understanding of the observed objects.
About Angles form Wiki
Textbooks of film appreciation never fail to mention camera height as an important means of expression in cinematography. A high angle, it is said, makes the subject look small and insignificant, a low angle makes it look imposing and awesome:'Low angles generally give an impression of superiority, exaltation and triumph...high angles tend to diminish the individual, to flatten him morally by reducing him to ground level, to render him as caught in an insurmountable determinism'(Martin 1068:37-8).But this leaves the viewer out of the picture.
Vertical Angles
Vertical viewing angle performance of observers is more the status, performance of power relations.
Horizontal Angles
Frontal:Involved-Direct
More of a positive angle viewer and observed interaction between objects, Direct Gaze is one of the most intense relationship of mutual influence.
Oblique:Detached-Indirect
Although this picture is a positive view, but the sight of the characters in the picture is higher than the viewer, so this picture is an attempt to influence the performance of the audience's way of life.